import java.nio.file.attribute.PosixFileAttributes;
import java.text.ParseException;

/**
 * Created with IntelliJ IDEA.
 * Description:
 * User: DELL
 * Date: 2022-09-30
 * Time: 9:19
 */
public class LinkedList {

    static class ListNode {

        public int val;
        public ListNode prev;// 前驱
        public ListNode next;// 后驱
        public ListNode(int val) {
            this.val = val;
        }

    }

    public ListNode head;   //头节点
    public ListNode tail;   //尾节点

    //头插法
    public void addFirst(int data){
        ListNode node = new ListNode(data);
        if(head == null){
            this.head = node;
            this.tail = node;
        }else{
            node.next = this.head;
            this.head.prev = node;
            this.head = node;
        }
    }
    //尾插法
    public void addLast(int data){
        ListNode node = new ListNode(data);
        if(this.head == null){
            addFirst(data);
        }else {
            this.tail.next = node;
            node.prev = this.tail.prev;
            this.tail = node;
        }
    }

    //任意位置插入,第一个数据节点为0号下标
    public void addIndex(int index,int data){
        if(index < 0 || index > size()){
            throw new IndexIlligelException("pos位置不合法！");
        }

        if(index == 0){
            addFirst(data);
            return;
        }
        if(index == size()){
            addLast(data);
            return;
        }

        ListNode cur = findindex(index);
        ListNode node = new ListNode(data);

        node.next = cur;
        cur.prev.next = node;
        node.prev = cur.prev;
        cur.prev = node;
    }
    public ListNode findindex(int index){

        ListNode cur = this.head;
        //找不到得情况下 cur可能会不合法！
        while((index--) != 0){
            cur = cur.next;
        }
        return cur;
    }
    //查找是否包含关键字key是否在单链表当中
    public boolean contains(int key){
        if(head == null){
            throw new EmptyException("链表为空！");
        }

        ListNode cur = this.head;
        while(cur != null){
            if(cur.val == key){
                return true;
            }
            cur = cur.next;
        }
        return false;
    }
    //删除第一次出现关键字为key的节点
    public void remove(int key){
        ListNode cur = this.head;
        while(cur != null){
            //找到了
            if(cur.val == key){
                //在头节点
                if(cur == head){
                    this.head = head.next;
                    if(head == null){
                        this.tail = null;
                    }else{
                        this.head.prev = null;
                    }
                }
                //不在头节点
                else {
                    cur.prev.next = cur.next;
                    //不在尾节点
                    if(cur.next != null){
                        cur.next.prev = cur.prev;

                    }
                    //在尾节点
                    else {
                        this.tail = cur.prev;
                    }
                }
                return;
            }
            //找不到
            else{
                cur = cur.next;
            }
        }
        System.out.println("链表中不存在要删除的值为"+key+"的节点！");
    }
    //删除所有值为key的节点
    public void removeAllKey(int key){

        ListNode cur = this.head;
        while(cur != null){
            //找到了
            if(cur.val == key){
                //在头节点
                if(cur == head){
                    this.head = head.next;
                    if(head == null){
                        this.tail = null;
                    }else{
                        this.head.prev = null;
                    }
                }
                //不在头节点
                else {
                    cur.prev.next = cur.next;
                    //不在尾节点
                    if(cur.next != null){
                        cur.next.prev = cur.prev;

                    }
                    //在尾节点
                    else {
                        this.tail = cur.prev;
                    }
                }

            }
            //找不到

                cur = cur.next;

        }
    }
    //得到单链表的长度
    public int size() {
        ListNode cur = this.head;
        int count = 0;
        while (cur != null) {
            count++;
            cur = cur.next;
        }
        return count;
    }

    public void display(){
        ListNode cur = this.head;
        while(cur != null){
            System.out.print(cur.val+" ");
            cur = cur.next;
        }
        System.out.println();
    }

    public void clear(){
        ListNode cur = this.head;
        while(cur!=null){
            ListNode curNext = cur.next;
            cur.next = null;
            cur.prev = null;
            cur = curNext;
        }
        head = null;
        tail = null;
    }

}
